Airflow arrangement for a refrigerator

ABSTRACT

A refrigerated display cabinet ( 10 ) has a chamber ( 12 ) accessible via the doors ( 12 ) of the cabinet. The bottommost shelf ( 16 ) in the chamber is a substantially imperforate shelf which is spaced from the bottom wall ( 17 ) of the chamber to form a duct-like passage through which air is drawn by a fan ( 15 ). The air is directed past an evaporator ( 17 ) of a refrigerating mechanism so as to be cooled. The cooled air is recirculated into the chamber ( 12 ) by passing it through apertures in a perforate inclined rear internal wall ( 18 ) of the chamber. The remainder of the cooled air is directed downwardly through openings ( 24 ) at the top of the chamber past the front of the shelves.

[0001] This invention relates to improved airflow in refrigerated cabinets. In particular, the invention is directed to improvements in the design of refrigerated cabinets to improve airflow, and thereby provide more efficient and uniform cooling of the contents of the cabinet.

BACKGROUND ART

[0002] Upright refrigerated display cabinets, such as commercial refrigerators, typically have several vertically spaced shelves, each adapted to hold several rows of products to be kept refrigerated while they are displayed for sale. Cooled air is circulated through the cabinet chamber to provide as uniform cooling of the contents as possible. The airflow is typically created by a fan which draws air from the cabinet chamber and blows it through the evaporator of a refrigerating mechanism. The air, after being cooled by its passage through the evaporator, flows back into the chamber to cool the products in the cabinet.

[0003] Products on the shelves are subjected to different and varying thermal effects. For example, the temperature of the products at the front of the shelves may be affected by the repeated and/or prolonged opening of the refrigerator doors. Products at the back of a crowded shelf may be shielded from the cooling airflow, or shield other products from the airflow. Some manufacturers, e.g. suppliers of canned softdrinks, insist that their products only be displayed in refrigerators which can provide uniform cooling.

[0004] Although there are many known designs of refrigerated cabinets which utilise re-circulating airflow to cool the products, it has been found that thermal distribution is rarely uniform, and hence the cooling is not even throughout the refrigerated cabinet. Moreover, the cooling patterns in known refrigerated cabinets are often affected by the amount and placement of products in the refrigerated cabinet.

[0005] It is an object of this invention to provide an improved design for a refrigerated cabinet which promotes better internal airflow within the cabinet, and hence more uniform cooling.

SUMMARY OF THE INVENTION

[0006] In one broad form, this invention provides a refrigerated cabinet having

[0007] a housing with internal walls defining a chamber closed by at least one door of the refrigerated cabinet,

[0008] a refrigerating mechanism including an evaporator, and

[0009] fan means for creating a flow of air from the chamber, past the evaporator so as to be cooled thereby, and back to the chamber,

[0010] characterised in that the cabinet includes a substantially imperforate shelf extending horizontally across a major part of the chamber, the shelf being adjacent to, but spaced from, the horizontal internal wall of the chamber which is nearest the evaporator, such that a duct-like passage is formed between the shelf and said wall for channeling the airflow to the evaporator.

[0011] The term “substantially imperforate” is intended to mean that the shelf is, for practical purposes, a solid continuous shelf with no significant openings. The shelf may contain one or more relatively small openings, e.g. for drainage, which do not permit significant airflow therethrough. In other words, the shelf effectively remains a substantially continuous layer which does not permit any substantial airflow therethrough.

[0012] Typically, the evaporator is located under the refrigerated chamber, and the duct-like passage is formed between the bottom shelf in the chamber and the bottom wall of the chamber. Unlike known refrigerated cabinets in which the bottom shelf is perforated, foraminous or grid-like in the same manner as the other shelves, the bottom shelf of this invention is a substantially imperforate layer. Hence, the air must flow around the front edge of the shelf. It is believed that this helps promote better airflow through the chamber.

[0013] Preferably, the chamber has an inclined perforated rear internal wall, and the cooled airflow from the evaporator is directed through the perforated rear wall back into the chamber. The inclined perforated rear wall helps distribute the cooled air to all of the shelves.

[0014] Preferably, a curved wall is provided between the evaporator and the perforated rear wall to curl the airflow from the evaporator along, and partially into, the perforated wall. The curved wall provides a smoother directional change to the airflow. It is believed that this results in less thermal exchange at this location, enabling the airflow to be of greater cooling effect subsequently in the cabinet chamber.

[0015] Preferably, a portion of the airflow into the chamber is directed vertically along the front of the chamber between the shelves and the door(s). Typically, the air is directed downwardly from the top of the chamber. In a preferred embodiment, the air flows along a horizontal duct at the top of the chamber. A ramp at the end of the duct reduces the cross-sectional area of the duct. The airflow is lifted and concentrated, before being directed downwardly in front of the shelves. The cooled air not only acts as an “curtain”, but also helps cool these items at the front of the shelves.

[0016] In order that the invention may be more fully understood and put into practice, a preferred embodiment will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a perspective view from above of a refrigerated cabinet according to one embodiment of the invention,

[0018]FIG. 2 is a perspective view from below of the refrigerated cabinet of FIG. 1, and

[0019]FIG. 3 is a schematic sectional elevation of the refrigerated cabinet of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT

[0020] As shown in the drawings, a refrigerated cabinet 10 comprises a housing 11 having internal top, bottom, side and rear walls defining a chamber 12 which is closed by a pair of glass doors 13. The chamber typically includes several vertically spaced shelves (which are omitted from FIGS. 1 and 2 for clarity). These shelves are usually in the form of grills or perforated sheet metal to enable condensation on the products to fall through to the bottom of the chamber.

[0021] A refrigerating mechanism is located under the chamber 12. The refrigerating mechanism includes an evaporator 14, typically of grid-like form and/or with cooling fins to maximise heat exchange with air passing through or along the evaporator. A fan 15 is provided to draw air from the chamber 12 and pass it through or along the evaporator 14 to thereby cool the air.

[0022] In accordance with the invention, the lowermost shelf 16 in the chamber 12 is a substantially imperforate shelf extending from a rear internal wall 18 to close to the door 13, i.e. across the major part of the chamber 12. The shelf 16 is spaced from the bottom wall 17 of the chamber to effectively form a duct-like passage therebetween.

[0023] Surprisingly, it has been found that the duct-like passage between the bottom shelf 16 and the bottom wall 17 significantly improves airflow and cooling within the chamber 16. The precise reason for such improvement is not known, but it may be due to one or more of the following factors.

[0024] The duct channels the airflow to the fan 15 in a more concentrated form. This enables the fan to create a greater flow of air.

[0025] The air is drawn from around the front edge of the shelf 16. Thus, the air must flow from the back of the shelf to the front thereof. This lateral flow across the shelf ensures that the products on the shelf are uniformly cooled, regardless of whether they are at the front or back of the shelf.

[0026] The flow of air from the front of the shelf 16 through the duct-like passage helps balance the pressures and velocity of air throughout the whole internal chamber 12, leading to more uniform cooling.

[0027] After the air has passed through the evaporator 14, it is directed upwardly into an upright air duct formed between the internal rear wall 18 and the rear wall of the housing 19. The wall 18 is a perforated or otherwise foraminous wall as can be seen in FIGS. 1 and 2. The perforated internal wall 18 is inclined. Hence, as the air flows upwardly, a component of the airflow passes through the perforations into the chamber 12 to cool the products on the shelves.

[0028] A curved wall 20 is provided between the evaporator and the upright duct in order to facilitate the directional change in airflow, as can be seen more clearly in FIG. 3. The smooth curvature of the curved wall 20 minimises turbulence in the airflow as it changes direction, and hence reduces heat exchange at that location. Consequently, greater heat exchange is able to be achieved later in the chamber 12, where it is desired. Moreover, the curvature of the curved wall 20 is such that it not only curls the airflow upwardly, but also slightly into the internal rear wall 18.

[0029] It is to be noted that the cross-sectional area of the vertical duct reduces with height. For constant airflow, the pressure would otherwise be greater at the top of the vertical duct than at the bottom, but air is progressively “lost” to the chamber as it flows up the duct. The tapered duct compensates for the loss of pressure due to air passing into the chamber 12 along the length of the vertical duct. The air pressure and velocity are therefore maintained fairly constant, and the cooled air is distributed evenly to the shelves along the rear wall 18.

[0030] A horizontal duct is formed between an internal top wall 21 and the top wall 22 of the housing 11. As the air flows along this duct to the front thereof, it is ramped upwardly and concentrated by a ramp-like formation 23 at the front end of the duct. The airflow is then directed downwardly through a row of holes 24 to form an “air curtain” along the front of the chamber 12. It has been found that the ramp formation 23 helps provide a more defined and uniform downward flow of air at the front of the chamber 12. This flow of air also helps cool the items at the front of the shelf which are furtherest away from the flow of air through the rear internal wall 18.

[0031] The air is continually recycled between the chamber 12 and the evaporator 14 as described above. It has been found that the above described arrangement assists in balancing the pressures and velocity of air throughout the whole chamber 12, and thereby provides a more uniform cooling of the chamber 12.

[0032] The foregoing describes only one embodiment of the invention, and modifications which are obvious to those skilled in the art may be made thereto without departing from the scope of the invention as defined in the claims appended hereto. For example, the evaporator may be provided above the refrigerated space to receive air through a duct-like passage between a solid top shelf and the top wall of the housing. The airflow would be inverted to that shown in FIG. 3. 

1. A refrigerated cabinet having a housing with internal walls defining a chamber closed by at least one door of the refrigerated cabinet, a refrigerating mechanism including an evaporator, and fan means for creating a flow of air from the chamber, past the evaporator so as to be cooled thereby, and back to the chamber, wherein the cabinet includes a substantially imperforate shelf extending horizontally across a major part of the chamber, the shelf being adjacent to, but spaced from, the horizontal internal wall of the chamber which is nearest the evaporator, such that a duct-like passage is formed between the shelf and said wall for channeling the airflow to the evaporator.
 2. A refrigerated cabinet as claimed in claim 1 , wherein the evaporator is located under the chamber, and the duct-like passage is formed between the lowermost shelf in the chamber and the bottom internal wall of the chamber.
 3. A refrigerated cabinet as claimed in claim 1 , wherein the chamber has an inclined perforated rear internal wall, and at least part of the cooled airflow from the evaporator is directed through the inclined perforated rear wall back into the chamber.
 4. A refrigerated cabinet as claimed in claim 3 , wherein the inclined perforated rear internal wall forms part of a duct having a cross sectional area which reduces progressively in the upward direction.
 5. A refrigerated cabinet as claimed in claim 4 , further comprising an airflow passage between the evaporator and the upright duct, the passage including a curved wall providing a directional change to the airflow prior to entering the upright duct.
 6. A refrigerated cabinet as claimed in claim 1 , wherein at least a portion of the cooled airflow is directed back into the chamber by being directed vertically along the front of the chamber.
 7. A refrigerated cabinet as claimed in claim 6 , wherein said portion of the airflow is directed downwardly from openings adjacent the top of the chamber.
 8. A refrigerated cabinet as claimed in claim 7 wherein said portion of the airflow flows along a horizontal duct at the top of the chamber before being directed downwardly at the front of the chamber.
 9. A refrigerated cabinet as claimed in claim 8 , further comprising a formation at the outlet end of the horizontal duct for ramping the airflow upwardly before it is directed downwardly into the chamber.
 10. A refrigerated cabinet having internal walls, including a bottom wall, defining a refrigerated chamber within the cabinet, a refrigerating mechanism including an evaporator located below the chamber, and a substantially imperforate shelf extending horizontally across a major part of the chamber, the shelf being the lowermost shelf in the chamber and spaced from the bottom wall so as to form a duct-like passage between the shelf and the bottom wall which communicates with the evaporator.
 11. A refrigerated cabinet as claimed in claim 10 , wherein a rear wall of the chamber is an inclined perforate wall permitting cooled air to flow into the chamber through perforations therein.
 12. A refrigerated display cabinet having internal walls, including a bottom wall, defining a refrigerated chamber, the chamber having a plurality of generally horizontal, vertically spaced, shelves, the bottom shelf in the chamber being substantially imperforate and extending from the rear wall of the chamber to near the front of the chamber so as to form a duct-like passage between the bottom shelf and the bottom wall, a refrigerating mechanism having an evaporator located below the chamber, a fan communicating with the duct-like passage to create a flow of air from the duct-like passage, past the evaporator to be cooled thereby, and back into the chamber, a rear internal wall of the chamber having openings therein to permit at least a portion of the cooled airflow to enter the chamber through said openings, and an opening located at the top of the chamber through which the remainder of the cooled airflow is directed downwardly into the chamber at the front of the shelves. 